There has been a conventional air conditioner in which: an auxiliary heat exchanger is disposed rearward of a main heat exchanger; and a refrigerant evaporates only in the auxiliary heat exchanger to locally perform dehumidification so that dehumidification can be performed even under a low load (even when the number of revolution of a compressor is small), for example, when the difference between room temperature and a set temperature is sufficiently small and therefore the required cooling capacity is small. In this air conditioner, an evaporation region is limited to be within the auxiliary heat exchanger, and a temperature sensor is disposed downstream of the evaporation region, to make control so that the superheat degree is constant.